Research round-up: genetics, comorbidities and more
June 30, 2017
Each month Action for M.E. publishes a round-up of research-related news written by our volunteer Emily Beardall, covering a selection of papers published in peer-reviewed journals.
Please note this is not an exhaustive list – we have selected to highlight the studies that we think are most likely to resonate with the daily lives of those affected by the condition. We will also report separately on further studies of significance, as and when they are published.
You can search online directory PubMed for most studies about M.E. published in peer-reviewed journals.
The following studies were published online between 22 April and 16 June 2017. In each case, we have used the same name for the illness as the researchers publishing the paper.
The genetics of fatigue
Studying twins can reveal to what extent a condition is purely due to the environment people have grown up in and their lifestyle, or whether there are additional genetic factors. A paper published in Twin research and human genetics looked at identical and non-identical twins with and without any fatiguing condition.
Researchers wanted to find out whether all fatiguing conditions have a common genetic link, unlike previous studies which have looked specifically at CFS. They found that fatigue conditions are familial, with genetics playing an important role in their cause, and that heritability of fatigue is the same for males and females.
Sleep patterns in teenagers with CFS
A study in the Journal of Sleep Research compared sleep patterns in teenagers with CFS and healthy controls. The participants wore a device that measures activity and completed a sleep questionnaire over a week. The readings from the device were used to estimate mid-sleep time, which is the mid-point of a period of sleep and time spent resting in bed.
The teenagers with CFS spent more time in bed but took longer to get to sleep and had a more varied mid-sleep time than the healthy teenagers. They also reported waking up more during the night, feeling less refreshed by sleep and more daytime sleepiness. The authors suggest that a sleep disorder may be a cause of CFS in teenagers.
Sub-groups by comorbidities
A study investigating comorbidities (ie. additional conditions) in people with CFS/M.E. was published in the journal Psychosomatics. By analysing questionnaires of more than 1,700 participants with CFS/M.E., the authors found that 80% had comorbidities and they defined five sub-groups:
1.Pain conditions (eg. fibromyalgia, myofascial pain, epicondylitis) and immune system conditions (eg. multiple chemical hypersensitivity, sicca syndrome, and thyroiditis)
2.Hypermobility and other connective tissue disorders, vitamin D deficiency, psychopathology and endometriosis
3.Very low presence of comorbidity
4.Poorly-defined comorbidities spanning the other groups
5.Metabolic syndrome, with high cholesterol levels
The authors noted that people in groups 1 and 2 tended to be older women who are unable to work, have high levels of fatigue, and a lower quality of life. Whereas group 3 was mainly comprised of younger, university student age, with lower fatigue scores and a better quality of life.
Gut bacteria and irritable bowel syndrome in M.E./CFS
A study in the journal Microbiome looked at links between abnormalities in the balance of gut bacteria (based on findings from previous studies), the immune system and metabolic pathways in people with M.E.
They found that patterns in the abnormal balance of gut bacteria varied depending whether the patients have irritable bowel syndrome (IBS) alongside M.E./CFS. The altered metabolic pathways for certain vitamins, for example, may be unique to M.E./CFS, while others may be linked to their IBS. The authors state that identification of networks that link gut bacteria, metabolic pathways and immune system molecules may help more accurate diagnosis into sub-groups and the development of treatments.
Similarities with other neurological illness
D-lactic acidosis is a rare condition where a build-up of lactic acid (produced by fermentation of carbohydrates in the bowel) causes a high concentration in the bloodstream, leading to symptoms such as fatigue, brain-fog, digestion problems and many other symptoms in common with M.E./CFS.
A review in the Journal of Translational Medicine explores these overlapping conditions, with the authors suggesting that a sub-group of people with M.E./CFS could lie on a spectrum between acute D-lactic acidosis and chronic M.E./CFS, or that this might be a factor which perpetuates or worsens neurological symptoms. Measurement of D-lactate in people with CFS/M.E. would be needed to confirm this theory.
Experiences of healthcare: two studies
A study in the journal BMC Family Practice has examined how people with CFS/M.E. use healthcare resources before and after receiving their diagnosis.
Using the Clinical Practice Research Datalink (CPRD), a secure database of anonymised medical records from 1987 to the present, gathered from hundreds of GP practices across the UK, researchers looked at rates of GP appointments, tests, prescriptions, referrals and symptoms.
They found that adults and children with CFS/M.E. had greater health care needs for at least ten years before their diagnosis, continuing for at least ten years after. This pattern was broadly similar in men and women and, they suggest, raises interesting questions about the natural history of CFS/M.E.
A further study about use of healthcare resources – this time patients’ experiences of NHS specialist CFS/M.E. services – was published in the journal BMC Health Services Research.
It found that people had a difficult journey before being referred, encountering disbelief and a lack of medical and social support. Once they accessed the specialist service, patients found restricting their activity and accepting their illness to be difficult, particularly the loss of social networks and employment. Patients also found travelling to the clinics challenging, some needing two days to recover between appointments and they expressed concern about people with severe M.E. being unable to get to appointments, but those who had telephone or Skype appointments found this helpful.
The study found that patients viewed one-to-one sessions more positively than group sessions, and found staff to be compassionate and knowledgeable, often commenting that this was on contrast to the experiences they’ve had previously with other health professionals. Many worried about being discharged because they felt unsupported by GPs, family, friends, colleagues and employers, and said they really need ongoing support. The patients interviewed all had a positive experience of the specialist services, though the authors acknowledge that they only interviewed people who had completed all their sessions, and that more work needs to be done to explore the reasons people drop out.